The .45cal 170gr Picket conical Bullet

Untill recently I'd never heard of the 1848 Colt-Walker revolver firing anything other than round ball, boy was I mistaken.

One the most visually striking cap and ball revolver conical bullets is the 170gr Picket Bullet.

History
Conical bullets are longer than they are wide, so they weigh more than the round balls that served as bullets for several hundred years. But because they’re longer, they can also create more friction with the bore. When they’re loaded from the muzzle, this is a problem because it takes so much more force to seat them down on the powder that the effort will usually distort their noses, adding nothing to accuracy.
One early solution (ca. 1835) was the picket bullet, which is also called the sugar-loaf bullet due to its shape. It contacted the bore only at a narrow band near the base of the bullet. The rest of the side of the bullet did not touch the bore and, therefore, did not create any friction. Picket bullets were far more accurate at long range than round balls of the day. They pushed the maximum distance for accuracy from about 200 yards out to 330 yards. And they were also heavier in a given caliber, so they were deadlier on game in calibers that were too small for round balls. A .38-caliber round ball might be marginal for whitetail deer, but a .38-caliber picket bullet would be fine.

The picket bullet looks like a large piece of candy corn. It was a big advance from the round lead ball. Image from Ned H. Robert’s book, “The Muzzle-Loading Cap Lock Rifle.”​

But there was a problem. If you tilted the picket bullet during loading — something that was all too easy to do, it left the bore in a tilted position, allowing gas to escape unevenly at the muzzle. That caused it to fly wide of its mark. Picket bullets were considered very accurate but also very difficult to load correctly.